Preparation of strontium hexaferrite magnets from celestite and blue dust by mechanochemical route

In the present investigation celestite (natural ore of strontium) and blue dust (iron ore fines) have been used for the preparation of strontium hexaferrite powder. The mechanical alloying process has been adopted to prepare strontium hexaferrite powder. The celestite after chemical upradation and physically upgraded blue dust alongwith sodium carbonate was taken for the preparation of strontium hexaferrite in this experiment. The high-energy planetary ball mill with tungsten carbide jar and ball was used to prepare strontium hexaferrite powder. A long time of ball milling for different duration has led to displacement solid-state reaction. At the end of each experiment the product was washed thoroughly and dried. The X-ray diffaction study after annealing shows the development of single-phase strontium hexaferrite after 40 hrs. of milling. The resultant powder was compacted under magnetic field and sintered to prepare the magnet after annealing the ferrite powder. The magnetic properties were measured by Pulse magneto meter. The moderate value of coercivity, remanence and energy product were observed in this sintered magnet. The work illustrates the feasibility to prepare strontium hexaferrite magnetic powders directly from natural ores which can reduce the total cost of production as compared to conventional method

Stabilization of a Highly Concentrated Colloidal Suspension of Pristine Metallic Nanoparticles

A colloidal suspension containing a high concentration of metallic nanoparticles (NPs) finds potential applications in flexible electronic printing, nanofluids, healthcare, antifouling coating, and so on. Here, we demonstrate a generic, easily scalable, simple, and contamination-free cryogenic temperature grinding method, which can effectively be used to prepare pristine NPs that can be stabilized in polar liquids in high concentrations. These surfactant-free pristine NPs have been found to remain dispersed in different polar liquids (CH3OH, C2H5OH, glycol, etc.) for weeks. The long-term stability of the NPs in these liquids has been investigated using zeta potential, in situ Fourier transform infrared spectroscopy, indicating electrostatic stabilization for ultrapure, surfactant-free NPs. Furthermore, stabilization of the NPs has been probed with detailed calculations using the Derjaguin Landau Verwey Overbeek theory as well as atomistic molecular dynamics simulation (MD). Experimental measurements along with theoretical calculations categorically indicate that the electrostatic energy is helping these NPs to be stabilized in a polar liquid

Predicting drainage quality for sustainable exploitation of coal

In this paper, a technique has been suggested to know the quality of mine drainage even before the start of mining operation. The coal and associated rock samples are collected from the mine site. The mineralogical composition and geochemical character of each rock types occurring at the site are determined. The geo-chemical properties are measured in terms of R-pH, pollution production potential (PPP) and acid neutralization potential (ANP). The geo-chemical characteristics of various rock types indicate that they have different geo-chemical properties. There is a discrepancy in pH values obtained under laboratory conditions and field data and an explanation is given. On the basis of geo-chemical properties and weathering tests, it is found that except sandstone, all other litho-types such as, coal shale, and shaly coal have the potential to deteriorate water quality and whatever the water pollutants present in the mine water are just because of interaction of these rock units with water. It is predicted that drainage from coal, shale, and shaly coal may be acidic, whereas drainage from sandstone is basic. The more or less same patterns are observed in the field. The technique suggested for the prediction of drainage quality may prove helpful and can identify rock types likely to produce water contaminants during their exposure to atmosphere in amine

Development of simplified WQIs for assessment of spatial and temporal variations of surface water quality in upper Damodar river basin, eastern India

In this study, four surface water quality datasets of upper Damodar river basin (DRB) covering three seasons; pre-monsoon, monsoon, post-monsoon and annual, for years 2007–2010 were generated by analyzing 280 grab water samples. Each dataset consist of water quality constituents of 35 monitoring stations and sample of each station was evaluated by 17 critical parameters (total 4760 observations). Furthermore, each dataset was treated using six water quality indices (WQIs): four developed simplified indices (WQIm, WQImin, WQIDO, and WQIpca) and two existing extended indices (WQIobj and WQIsub), to assess spatiotemporal variations and suitability for human use and aquatic life. Results revealed that developed indices show on an average similar spatiotemporal variations as compared to WQIobj at a lower analytical cost at most of sampling sites comes under good to medium categories of water quality. Geographical information system (GIS) technique was also used for generation of temporal pollution potential maps of DRB. Consequently, this study also presents the necessity and usefulness of developed indices over extended indices especially for the developing countries, because the cost of monitoring and expenses associated with the implementation is less compared to extended methods and generated maps may also facilitate the decision-making processes under various scenarios considering spatial and temporal variability in DRB

Evaluation of Water Quality Index of Damodar River for Drinking Purpose Using Computer Programming

The objective of the study is to evaluate and compare the water quality of river Damodar for drinking purposes using Water Quality Index (WQI) and Sensitivity Index (SI) respectively. WQI gives information about spatial and seasonal variations of pollution load and to classify river water into five classes: Excellent, Acceptable, Slightly polluted, Polluted and Heavily polluted for drinking purposes. However, SI gives an idea about whether quality of water is increasing or decreasing at same point during subsequent monitoring. Both were estimated using two separate computer programs; written in Clanguage based on the eleven water quality parameters such as pH, DO, BOD5, TDS, TSS, Cl^-, NO_3^ -- N, SO_4^{2-}, THARD, T-alkalinity, and T-coliform. A total 76 water samples were collected from 19 sampling points of a stretch D/S Tenughat dam to D/S Barakar river in mid-upper Damodar Valley to estimate spatial and seasonal variations in water quality for the year 2010. The values of WQI were found in the range of 66.2-75.6 in summer, while it was 55-76.0 in winter, affected mainly due to high values of total coliform, TSS and pH, exceeded the tolerable limits of IS:10:500 (1993) at almost all the sampling points. The results indicate that all sampling points were falling in the Acceptable (C2) to Slightly polluted (C3) range, except at Garga Nalla [Polluted (C4) category]. This study demonstrates the application of WQI using computer programming tool for quick assessment of water quality of any water body and also can be used for effective water quality management

Genesis of pyrites in coal and their relation with acid drainage from mine

The acid mine drainage problem could be solved to a certain extent only when occurrence and genesis of pyrite in coal are investigated properly. The relationship between genesis and occurrence of pyrite with acid mien drainage is discussed in this paper. Coal and water samples were collected from four mines and analysed. In coal, thoal sulphur content was analysed. In the sump water, temperature, pH value, conductivity and TDS were determined. The concentrations of sulphate and iron were analysed and values were correlated with total sulphur content in coal. In this work, an attempt is made to establish a relation between total sulphur content in coal with pH value and sulphate concentration of mine water. The genesis of sulphides in coal of Gorbi and Jhingurdah projects of singrauli coalfield is also discussed. The genesis of pyrite (sulphides) in coal suggest that in isolated small basin, there was favourable condition for pyrite mineralization and thereby more sulphur were found in coal deposits in Gorbi and Jhingurdah basins as compared to Amlori and Jayant projects of main basin of deposition. The occurrence of pyrites is mostly in the form of thin layer along cleats and beds occurring parallel to weak planes in coal seam. In some coal samples, laminated and disseminated sulphides are also common and is the main cause of acidity in sump water. There is direct relationship between total sulphur in coal and mine water quality parameters, ie, pH, TDS and suphate etc. the genesis and occurrence of sulphides in coal seam and characteristics of sump water were determined in order to predict the acidity of mine water for development of coal project management plan of acid mine water at early stages

ENVIRONMENTAL IMPACT OF COAL MINING ONWATER REGIME AND ITS MANAGEMENT

Coal mining is one of the core industries that contribute to the economic development of a country but deteriorate the environment. Being the primary source of energy coal has become essential to meet the energy demand of a country. It is excavated by both opencast and underground mining methods and affects the environment, especially water resources, by discharging huge amounts of mine water. The mine water may be acidic or neutral depending upon the pyrite content in the coal as inorganic impurities. Acid mine drainage occurs in those mines in which sulphur content is found in the range of 1–5% in the form of Pyrite (FeS2). It degrades the water quality of the region in terms of lowering the pH of the surrounding water resources and increasing the level of total suspended solids, total dissolved solids and some heavy metals. In non acidic mines, water quality shows high hardness, TSS and bacterial contaminants. The leachate water from overburden dump are found enriched in metal concentration especially Fe, Cu, Mn and Ni except in one of the clayey dumps. High values of hardness of mine water reduces it’s utility in domestic purposes. The article illustrates the quality of acidic and non acidic mine water and leachate characteristics of opencast coal mining OB dumps. Pollutants such as TSS, TDS, oil and grease and heavy metal are found in the coal mining waste effluents. Management of these liquid waste at the primary level and secondary level have also been suggested to control the pollution level at the source

Physico-Chemical Analysis and Correlation Study of Water Resources of the Sukinda Chromite Mining Area, Odisha, India

The Sukinda Valley of the Jajpur district of Odisha produces 98 % of India’s chromite ore. The region’s groundwater and Damsal Nala, the valley’s primary stream, have been contaminated by Cr(VI) due to surface runoff and leachates from overburden dumps. Samples of mine water, surface water, and groundwater were analyzed. The concentration of total Cr in the mine water ranged from 0.46 to 1.26 mg/L before treatment and between 0.03 and 0.45 mg/L after treatment. Effluent Cr(VI) ranged between 0.02 and 0.3 mg/L. Thus, discharge water at some mine sites still contain Cr(VI) at concentrations above the permissible effluent limits of 0.1 mg/L for inland surface water. Concentrations of Cr(VI) ranged from 0.02 to 0.23 mg/L in the Damsal Nala and nil to 0.13 mg/L in tube well water, sometimes exceeding the permissible limits, but were acceptable in dug wells. Pearson’s correlation analysis revealed that Cr(VI) positively correlated with sulfate (0.854) in surface water, hardness (0.379) and pH (0.361) in groundwater, and total Cr (0.970) in mine water

Effect of coal mining and coal based industrial activities on water quality of the river Damodar with specific reference to heavy metals

A study of water quality of the river Damodar in a stretch of 50 km in Jharia Coalfield region was carried out with specific reference to heavy metals. Sediments of the river bed was characterized for heavy metals, fe, Mn, Cd, Cr, Ni and Pb to determine total carry over of heavy metals in the river body. Industrial effluents have been characterised to see the level of pollution the river receiving. DO and BOD profile study.showed that the most vulnerable zone of the river was a stretch of 15 km in Jharia Coalfield. Organic pollution level of the river was found to be high during lean period resulting high values of BOD and COD. Heavy metal concentrations in the river sediments were found higher in comparison to the river water. Variation in concentration of metals in sediment and water was observed in different stretches of the river. The deposition of Cr in sediment was higher in downstream in comparison to other stretches. The study also reflected that Fe and Mn were irreversibly retained in the sediment and this effect was observed for other metals also in decreasing order of Pb, Cr, Ni and Cd

Managing aqueous solutions rich in Mn(II): An inexpensive technique

The ability of fly ash to remove manganese from aqueous solutions by adsorption was investigated. The extent of removal was dependent on concentration, pH and temperature of the solution. The applicability of the Langmuir isotherm to the fly ash-manganese system was tested at 30°C and pH 8.0. These were the optimum conditions for maximum removal. The values of the adsorptive capacity Q0 and bonding constant bwere found to be 0.20 mg g−1 and 1.25 mg−1 respectively under the above conditions. With an initial concentration of 1.0 mg l−1 and at 30°C and pH 8.0, the removal was found to be 80.0%. The time to reach equilibrium was 2 h. The process of uptake is governed by first-order rate kinetics and under optimum conditions the rate constant of the reaction was found to be 2.40•10−2 min−1. The pH dependence study revealed that at pH 8.0 the uptake was 80.0% but at pH 9.0, 99.0% removal was found. The higher uptake at pH 9.0 was attributed to adsorption coupled with hydrolysis followed by oxidation. The dibasic behaviour of fly ash also facilitated Mn(II) adsorption at higher pH owing to the low pH required for constant zeta potential